// in order to implement step4_Hello.c, i think it is best from a simplest one. it is step4_Hello_0.c

void main(){
  int a, b;
  a = 2;
  b = a + 3;
}

//   func main voidtype
//     stmtblock
//       vardef a
//       vardef b
//       assign
//         varref a
//	   intconst 2
//	 assign
//	   varref b
//	   add
//	     varref a
//	     intconst 3
